Polarization diversified antenna



Oct. 19, 1965 w, KORVIN 3,213,456

POLARI ZATION DIVERS IFIED ANTENNA Filed Feb. 25, 1965 LOCUS OF POINT OF E FIELD IN VENTOR.

WILLIAM KORVIN 22 FIG. 5 BY M M am cw/2 M A TTORNEYS' United States Patent C) 3,213,456 POLARIZATION DIVERSIFIED ANTENNA William Korvin, Baltimore, Md assignor to Martin Marietta Corporation, New York, N.Y., a corporation of Maryland Filed Feb. 25, 1963, Ser. No. 260,510 8 Claims. (Cl. 343-756) This invention relates to improvements in antennas, and more particularly to a polarization diversified antenna.

It is known to provide a polarization diversified radiating element by using various phasing arrangements and employing the basic configuration of the turnstile antenna. The turnstile antenna principle utilizes two half-wave resonant radiators crossing one another in the same plane and excited 90 out of phase with each other. Since the individual radiations are in time quadrature the total radiation has roughly a circular character and the field radiated in a direction at right angles to the plane of the turnstile array is circularly polarized. The turnstile principle has been widely used and is important because it provides a practical arrangement for obtaining a pattern which is approximately omni-directional in the plane in which the Wave is polarized and it also provides a simple means of generating a circularly polarized wave. However, the circular polarized wave will be polarized in either a righthand sense or a left-hand sense depending upon the connection of the transmission lines. In other words, it is known to diversify the polarization of a turnstile antenna by switching the transmission lines either by hand or by electrical switching arrangements. Of course, switching transmission lines by hand is quite time-consuming and not appropriate where polarization diversification is required in radiating elements in any degree of regularity. The alternative of providing electrical switches for the transmission lines causes arcing and a primary source of noise in the radiated signal. Thus, the known electrical switching arrangements for providing polarization diversification are primarily limited to relatively low RF power since the change or diversification of polarization accomplished through electrical switching obviously limits the power which can be available to the radiating element in addition to the resulting pulling of the transmitter due to arcing during the period of change of contacts.

This invention provides a polarization diversified radiating or receiving element employing the basic configuration of the turnstile antenna and utilizing mechanical rotation of paired elements of the turnstile antenna for ac complishing a change in polarization.

It is an object of this invention to provide a radiating antenna capable of polarization diversification while not creating arcing or introducing noise during a change in polarization and while not limited to comparatively low power.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a perspective view of the radiating element having provisions for mechanical switching or positioning for diversification of polarization which is the subject of this invention;

FIG. 2 is a diagrammatic top plan view of the antenna positioned for right-hand circular polarization;

FIG. 3 is a diagrammatic top plan view similar to FIG. 2 after the mechanical positioning of the radiating elements to produce left-hand circular polarization;

FIG. 4 is a diagrammatic elevational view with the radiating elements further positioned for providing linear polarization; and

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FIG. 5 is an elevation view of the antenna which has been positioned for providing linear polarization in another direction.

In general, this invention concerns a polarization diversified antenna using the various phasing arrangements as employed in the prior known turnstile antennas while modifying the turnstile antenna for mechanical movement and selective positioning of the orthogonal dipoles which are fed from the transmission lines in phase quadrature from a common signal source to thereby provide for left or right-hand circular polarization or orthogonal linear polarization.

Referring to the drawings, the antenna structure indicated generally at 10 is somewhat similar to the basic turnstile antenna. It may be, however, modified to provide polarization diversification in accordance with the teachings of this invention.

The antenna 10 includes a support mast 12 suitably mounted on any convenient support 14 which may be the ground or the like. The mast 12, however, is supported from support 14 so that it may be rotatable about the axis of mast 12 in either direction as shown by the arrows on the base of mast 12. A rotary solenoid 15 or other known drive means may conveniently be utilized for rotation of mast 12 in any increment of movement. The mast need not be vertical as shown but could extend in any direction depending upon the desired application of the antenna.

Extending transversely from the mast 12 are a pair of horizontal support arms 16 and 18. These support arms are rotatably journaled in the mast 12 and may be rotated from within the mast 12 by suitable means such as rotary solenoids 17 and 19 for positioning each arm in increments in either direction about its axis.

At the end of arm 18 is a support plate 20 mounting on one end thereof a radiating element 22 and on the other end thereof a radiating element 24. Radiating elements 22 and 24 are disposed at a substantial angle to one another, for example, 90. Similarly, at the outer end of support arm 16 is another support plate 26 and another pair of radiating elements 28 and 30.

Transmission lines, indicated generally at 32, feed into the mast 12 and then out from the mast for connection to the radiating elements 22, 24, 28 and 30. Particularly, transmission lines 34 and 36 energize radiating elements 22 and 24 at phase angles of 0 and 90 and the length of the transmission lines is equal to and these transmission lines or phasing cables may include a phase shifter to increase the frequency range of operation of the antenna above that range of a fixed length transmission line.

In a similar manner transmission lines 38 and 40, having a length of energize radiating elements 28 and 30 at phase angles of and 270. With this arrangement the arrows on FIG. 1 adjacent the radiating elements indicate that elements 24 and 30 are effective one dipole and elements 22 and 28 constitute the orthogonal dipole. Again, the transmission lines 38 and 40 are variable length by means of a phase shifter so that the frequency range of operation of the antenna may be increased.

FIG. 2 shows the arrangement of FIG. 1 diagrammatically, and with the radiating elements fed in phase quadrature as shown the radiated wave will be right-hand circularly polarized into the sheet of drawings and the locus point of the E-field will be as shown by the arrow.

aa aeae In FIG. 3 each of the arms 16 and 18 has been rotated 180 by the rotary solenoids 17 and 19 and the radiation produced when the antenna is energized in phase quadrature is left-hand circular polarization into the sheet of drawings and the locus point of the E-field is counterclockwise as shown by the arrow. All that is necessary to change from the FIG. 2 right-hand circular polarization to the FIG. 3 left-hand circular polarization is energization of the rotary solenoids 1'7 and 19 to rotate each of teh arms 16 and 18 through 180. During this mechanical switching or positioning operation no arcing would occur as with electrical switching.

FIG. 4 is an elevational view with the arms 16 and 18 rotated 90 in opposite directions from that shown in FIG. 3. With the arrangement of FIG. 4 there will be linear polarization in the plane of the drawings. In other words, by rotating radiating elements 22 and 24 clockwise 90 and radiating elements 28 and 30 counterclockwise 90 from that position shown in FIGS. 1 and 2 linear polarization may be produced.

By rotating the mast 12 through any increment additional linear polarizations may be obtained. As one example, the position of FIG. 4 could be rotated 90 by merely rotating the mast 90 a shown, for example, in FIG. 5.

Although rotary solenoid drive means have been disclosed for rotating the mast and arms, any positioning means including manually operated clamping means may be employed or the equivalent.

As can be seen from the foregoing, applicant has disclosed a unique arrangement for changing from left-hand sensed circular polarization to right-hand sensed circular polarization and to any linear polarization by means of mechanically positioning radiating elements without the necessity of electrical switching or manually changing of phasing transmission lines. The mechanical positioning or switching of the radiating elements in a predetermined manner results, therefore, in the capability of radiating or receiving left-hand circular, right-hand circular, any linear polarizations, or, if desired, elliptical polarization.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. A polarization diversified antenna comprising;

(a) a mast-mounted turnstile antenna arrangement including two orthogonal dipoles in phase quadrature,

(b) means mounting the turnstile antenna mast for rotation about its own axis for selective positioning, and

(c) means mounting an adjacent portion of a pair of orthogonal dipoles for rotation about an axis generally transverse to the mast axis to thereby provide polarization diversification by selective positioning of all mounting means.

2. A polarization diversified antenna comprising;

(a) a stationary support,

(b) mast rotatable relative to the support,

(c) a pair of rotatable horizontal supports extending from opposite sides of the mast,

(d) a pair of M4 wave length antenna elements extending from each support at 90 to each other,

(e) phasing lines connected to each pair of radiating elements for energizing the same from the same source in phase quadrature, and

(f) means for rotating said mast in increments in either direction, and

(g) means for rotating the horizontal supports in increments in either direction.

3. An antenna as defined in claim 2 wherein adjacent radiating elements on the separate supports are positionable 90 from one another. 1

4. A polarization diversified antenna as defined in claim 3 further comprising line stretcher means in transmission lines feeding the antenna elements.

5. A polarization diversified radiating antenna compris- (a) a rotatable mast,

(b) a pair of rotatable supports extending transversely from the mast,

(c) a pair of radiating elements extending from the supports at right angles to each other, and

(d) transmission phasing lines from the same source connected to each radiating element to energize the same in phase quadrature as a turnstile antenna to provide circular polarization of one sense in one position and by rotating the supports to provide circular polarization in the other sense while providing linear polarization by rotating both supports 90, and changing the linear polarization by rotating the mast.

6. An antenna as defined in claim 5 further comprising drive means for rotating the mast and drive means for separately rotating each of the supports.

7. An antenna as defined in claim 6 wherein all the drive means are rotary solenoids and radiating element supports are rotated in 90 increments in either direction.

8. A polarization diversified radiating antenna compris- 23;

(a) a rotatable antenna support shaft,

(b) a pair of radiating element support arms extending transversely from the shaft,

(c) means mounting each support arm for selective positioning about its own axis,

(d) a pair of radiating elements carried by each radiating element support and extending radially from the support shaft at right angles to each other, and

(e) transmission phasing lines from the same source energizing all radiating elements in time quadrature in the nature of a turnstile antenna so as to provide circular polarization of one sense in the position and by rotating one support arms 180 to provide circular polarization in the other sense while providing linear polarization by rotating both support arms 90, and changing the linear polarization by rotating the shaft.

References Cited by the Examiner UNITED STATES PATENTS 2,374,271 4/45 Brown 343-798 2,412,090 12/46 Kiblcr 343-797 2,512,682 6/50 Salinger et al. 343-797 2,661,423 12/53 Middlemark 343-797 FOREIGN PATENTS 187,559 12/54 Austria.

ELI LIEBERMAN, Primary Examiner.

HERMAN KARL SAALBACH, Examiner. 

1. A POLARIZATION DIVERSIFIED ANTENNA COMPRISING: (A) A MAST-MOUNTED TURNSTILE ANTENNA ARRANGEMENT INCLUDING TWO ORTHOGONAL DIPOLES IN PHASE QUADRATURE, (B) MEANS MOUNTING THE TURNSTILE ANTENNA MAST FOR ROTATION ABOUT ITS OWN AXIS FOR SELECTIVE POSITIONING, AND (C) MEANS MOUNTING AN ADJACENT PORTION OF A PAIR OF ORTHOGONAL DIPOLES FOR ROTATION ABOUT AN AXIS GENERALLY TRANSVERSE TO THE MAST AXIS TO THEREBY PROVIDE POLARIZATION DIVERSIFICATION BY SELECTIVE POSITIONING OF ALL MOUNTING MEANS. 